76 lines
3.1 KiB
Plaintext
76 lines
3.1 KiB
Plaintext
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the documentation of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:FDL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Free Documentation License Usage
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** Alternatively, this file may be used under the terms of the GNU Free
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** Documentation License version 1.3 as published by the Free Software
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** Foundation and appearing in the file included in the packaging of
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** this file. Please review the following information to ensure
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** the GNU Free Documentation License version 1.3 requirements
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** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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/*!
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\example widgets/digitalclock
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\title Digital Clock Example
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\ingroup examples-widgets
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\brief The Digital Clock example shows how to use QLCDNumber to display a
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number with LCD-like digits.
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\borderedimage digitalclock-example.png
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\caption Screenshot of the Digital Clock example
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This example also demonstrates how QTimer can be used to update a widget
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at regular intervals.
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\section1 DigitalClock Class Definition
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The \c DigitalClock class provides a clock widget showing the time with
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hours and minutes separated by a blinking colon. We subclass QLCDNumber
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and implement a private slot called \c showTime() to update the clock
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display:
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\snippet widgets/digitalclock/digitalclock.h 0
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\section1 DigitalClock Class Implementation
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\snippet widgets/digitalclock/digitalclock.cpp 0
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In the constructor, we first change the look of the LCD numbers. The
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QLCDNumber::Filled style produces raised segments filled with the
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foreground color (typically black). We also set up a one-second timer
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to keep track of the current time, and we connect
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its \l{QTimer::timeout()}{timeout()} signal to the private \c showTime() slot
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so that the display is updated every second. Then, we
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call the \c showTime() slot; without this call, there would be a one-second
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delay at startup before the time is shown.
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\snippet widgets/digitalclock/digitalclock.cpp 1
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\snippet widgets/digitalclock/digitalclock.cpp 2
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The \c showTime() slot is called whenever the clock display needs
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to be updated.
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The current time is converted into a string with the format "hh:mm".
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When QTime::second() is a even number, the colon in the string is
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replaced with a space. This makes the colon appear and vanish every
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other second.
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Finally, we call QLCDNumber::display() to update the widget.
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*/
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